Oh yes, 3 days on 60 lbs, You may well have 50 left
My rig has a 31 gallon tank, I usually refill long about 20 gallons or so I'm not sure what that translates to in LBS
I suspect with a sixty lb bottle you should be good for well over 3 nights
Suggestion.. if you are worried visit your RV supply store, Marshall Brass has a product called an "Extend-a-stay" it's a device that goes in the gas line, right at the POL valve, before the regulator, It comes in a couple of models.. The one I have has an Inlet fitting so you can hook an external tank to the rig (A hose is included) and an outlet (This is like the top of a 1lb Propane bottle) to hook up your grill as well as a POL fitting for the regulator to connect to, it also contains flow limiters (In case you blow a gas line) and check valves (to insure that inlets are just inlets and don't leak gas) Very handy
This easily installed device allows me to either run the portable grill off the rig's gas bottle, or inversely heat the rig using the portable grill's portable bottle. Works both ways. You might wish to look into one